The present invention relates to the general field of aircraft turboprops having two unducted propellers. More precisely, the invention relates to attaching such a turboprop to a structural element of the aircraft, such as the fuselage or a wing of an airplane.
In known manner, an aircraft turboprop having two propellers is a gas turbine aeroengine that generates its main thrust by means of two unducted contrarotating propellers that are positioned at the rear of the engine.
By way of example, such a turboprop may be attached to the fuselage of an aircraft via a pylon connected to a suspension structure, which structure is fastened directly to the engine.
Simulations of the dynamic behavior of the assembly made up of the turboprop and its suspension structure have revealed the presence of a vibration mode of the air intake structure of the turboprop that lies within the operating range of the engine. However, the presence of such a mode in the operating range of the engine has the effect of multiplying dynamic loads on certain bearings of the turboprop.
Unless made stiffer, thereby significantly increasing the second moment of area of a portion of the casing line, such engines are not all capable of withstanding such forces. Also, it is necessary to keep the vibration mode remote from the operating range of the engine. To do this, one solution consists in reducing the weight of the assembly. Nevertheless, it is usually not possible to achieve such weight reduction. Another solution consists in modifying the way the air intake is attached to the engine, e.g. by adding an additional partition. Nevertheless, none of the structures for attaching the inlet to the engine and that have been tested so far has been found to be effective in mitigating such a drawback.